Conventionally, “an alternating current (AC) charging technique” that applies a voltage of a direct current (DC) voltage component overlapped with an AC voltage component to a contact charging member has been used in order to improve charging evenness. However, since it is needed to use a high AC voltage having a peak-to-peak voltage that is twice or greater a discharge start voltage (Vth) of a DC voltage to be applied, a separate AC power supply, in addition to a DC power supply, is needed, which results in an increase in a cost of the device itself. Also, a large amount of close proximity discharging may occur between the charging member (e.g., a charging roller) and a photoconductor, and thus the durability of the charging roller or the photoconductor may deteriorate. In particular, the photoconductor may be easily abrased. The problem may be reduced by charging the charging roller by applying a DC voltage alone. For example, JP 2007-065469 A discloses a charging member that is used when charging is performed by applying a DC voltage alone thereto.